WO1999046956A1 - Boitier de microphone a capteur radial - Google Patents

Boitier de microphone a capteur radial Download PDF

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Publication number
WO1999046956A1
WO1999046956A1 PCT/CA1999/000186 CA9900186W WO9946956A1 WO 1999046956 A1 WO1999046956 A1 WO 1999046956A1 CA 9900186 W CA9900186 W CA 9900186W WO 9946956 A1 WO9946956 A1 WO 9946956A1
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WO
WIPO (PCT)
Prior art keywords
sound
channel
guide member
transducer
microphone
Prior art date
Application number
PCT/CA1999/000186
Other languages
English (en)
Inventor
Brian Turnbull
Dale Zimmerman
Original Assignee
Brian Turnbull
Dale Zimmerman
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Brian Turnbull, Dale Zimmerman filed Critical Brian Turnbull
Priority to AU27069/99A priority Critical patent/AU2706999A/en
Priority to EP99907196A priority patent/EP1062837A1/fr
Priority to US09/646,079 priority patent/US6681023B1/en
Priority to CA002321670A priority patent/CA2321670C/fr
Publication of WO1999046956A1 publication Critical patent/WO1999046956A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means
    • H04R1/342—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means for microphones

Definitions

  • the invention relates to a microphone system and more particularly to a microphone system which includes a microphone and a pair of dishes which channel the sound past the microphone.
  • US Patent no. 4,436,966, issued to Botros uses dishes with the sound being received within the concave portion of each of the two dishes to provide bi-directional reception. As the space between the dishes is a null region, the dishes can be in contact with one another without any loss of sound.
  • the microphone is positioned to respond to the sound coming into the concave portion of each dish, capturing the sound at the apex of the dishes.
  • the Botros dishes can be a portion of a small diameter sphere, or ellipse, with little concern as to depth of the dish Conversely, in the disclosed microphone enclosure, the angle of the waveguide must be shallow.
  • US Patent No. 4,831 ,656, to Southern et al discloses and claims an angle of about 22 degrees between a flat reflector plate and a cone
  • the predetermined 22 degree angle of the opening between the cone and the reflector plate controls the microphone's environment by deflecting the sound waves produced by conversations into the microphone mounted within the aperture of the cone.
  • sound waves enter the microphone directly, causing the microphone to produce a significantly higher electrical output in the voice frequency range.
  • the '656 patent further notes that the angle between the cone and reflector plate also produces uniform directional characteristics for the microphone
  • the 22 degree opening from the sides of the unit is the same at any point in a 360 degree plane creating a horizontal pattern that is uniformly radially directional
  • PZM microphones from CROWN (Model SOUNDGRABBER US Patent No. 4,361,736) or RADIO SHACK, and PHONIC EAR 2
  • Parabolic microphones have also been used to achieve long range pickup but do so in a very narrow directive pattern These microphones are also by necessity large They are impractical then for indoor conference and classroom applications, and outdoors only useful where directivity is desired
  • shotgun microphones are commonly used in long-range pickup situations They must be used in a large open area to function; they are highly directional, and often too large to be of use in classrooms or conference rooms As shown in comparisons the instant invention has a much higher acoustic gain than a shotgun microphone
  • the instant invention is capable of matching parabolic range in any pickup pattern variable to 360 degrees in a radial pattern Additionally the instant invention can match parabolic range in a package less than half the size
  • the disclosed invention therefore provides a microphone system having a sensitive, variable radial pickup pattern, which overcomes prior art shortcomings
  • the acoustical system of the invention converts sound waves into corresponding signals for use in acoustic data storage and/or driving a speaker
  • the conversion is only limited by available technology, and is most typically a conversion from sound to electrical signals
  • the system is equally applicable to a system which could directly convert the sound to laser beams or magnetic fields, or other form which is capable of being recorded in a data storage medium Magnetic tapes are commonly used for this purpose, but computer type disks can also be used for the storage of data
  • the form into which the sound is converted, whether it be optical or electrical, or some other form, is not narrowly critical
  • the system includes a housing which is formed from a pair of guide members It is believed that the pair of guide members act as a wave guide but an understanding of the functioning of the invention is not dependant the exact theory of operation
  • a first guide member is positioned proximate a second guide member, and is shaped relative to the second guide member, such that the distance between the first guide member and the second guide member, decreases in the direction of travel of the sound wave, that is, from the outer peripheral edge to inner region
  • the space 3 between said first guide member peripheral edge and said second guide means pe ⁇ pheral edge forms a sound wave entrance port
  • the transducer is positioned proximate the inner region between the two guide members, and is positioned to be responsive to sound waves which travel downstream, from said entrance port, past said transducer It is essential that the sound waves continue to travel past the transducer, rather than being reflected back in the upstream direction
  • each of said first guide member and said second guide member is a dish having a convex shape
  • each of the guide members has a peripheral edge which extends 360 degrees, thus producing an acoustical system which is radially directional
  • the guide members are convex dishes, and the transducer is position essentially at the center of the dishes
  • the sound channel is an open, 360 degree channel, in which sound waves enter the sound channel, travel past the transducer and continue to travel in the same direction until they exit the system, thereby forming an radially directional acoustical system
  • a pair of spaced apart side wails extend from, that is between, the first guide member and second guide member, and from the sound wave entrance port toward said transducer
  • the guide members are arcuate, that is, in the form of a segment of a pie Phrased another way, the sound channel, is arcuate, with the directionality of the acoustic system corresponding to the angle of the arc of the sound channel
  • a sound absorber is positioned down stream of the transducer to substantially preclude sound waves from reversing direction and traveling past said transducer toward said sound wave entrance port 4
  • the transducer is positioned within said channel, such that said transducer is activated normal to the direction of travel of said sound waves That is, the transducer is positioned such its active surface, typically a diaphragm, is at a right angle to the direction of travel of the sound waves
  • sound waves as used herein, is intended to be inclusive of pressure waves, which later term may more accurately define the wave form within the sound channel
  • the sound channel is understood to operate as a wave guide, but the scope of the invention is not limited to any particular theory of operation
  • the invention is the conversion of sound waves into corresponding signals of another form, as for example, electrical signals
  • the steps of the invention include guiding sound waves within a channel having a progressively decreasing cross-sectional area, from a channel entrance past a sound wave transducer, and precluding sound waves from re-traveling in the channel, from the transducer toward the channel entrance This is not intended to mean that the system cannot be an open system in which first sounds waves enter in a first direction and continue until they exit at
  • This aspect of the invention can be achieved by limiting sound waves entering the channel, to waves travel from a predetermined area, and absorbing sound waves which have traveled past said sound wave transducer Thus sound waves are precluded from re-traveling in said channel, from transducer toward the channel entrance
  • Figure 1 is a cross-sectional slice view of the disclosed invention with all components including a termination baffle
  • Figure 2 is a cross-sectional slice view of the disclosed invention in a 360- degree radial pickup
  • These input-exit channels are bi-directional as indicated by the arrows (10)
  • Figure 3 is a transparent perspective view of a directional embodiment showing the shape and position of one example of a termination baffle insert Solid arrows indicate sound pressure input, dotted arrows indicate sound pressure exit and diffusion
  • Figure 4 is a transparent perspective view of a 360-degree radial pickup 5 embodiment
  • Solid arrows indicate sound pressure input
  • dotted arrows indicate sound pressure exit
  • Figure 5 is a top cutaway view of directional embodiment with termination baffle insert as shown by hatched area
  • Figure 6 is a top cutaway view of a very directional embodiment with a termination baffle insert as shown by hatched area This figure when compared to figure 5 shows how pickup pattern can be varied by termination baffle shape and va ⁇ ed circumference of the dishes
  • Figure 7 is a top cutaway view of a 360-degree radial pickup microphone
  • Figure 8 is a top cutaway view of a 360-degree radial pickup with a va ⁇ ed circumference
  • Figure 9 shows blowup of the microphone element and the pressure channel (pressure chamber) in a single gap configuration
  • Figure 10 shows blowup of the microphone element and the pressure channel in a dual gap configuration
  • Figure 11 and figure 12 shows top cutaway and side cross-sectional views of a stereo multiple waveguide enclosure
  • Figure 13 and figure 14 shows top cutaway and side perspective views of a quadraphonic multiple waveguide enclosure
  • Figure 15 shows one version of a stacked multi-waveguide enclosure for a stereo coincident application
  • Figure 16 shows another version of a stacked multi-waveguide enclosure for a stereo coincident application using an inefficient non-symmetrical waveguide
  • Figure 17 is a top cutaway view showing a partition configuration and circumference shape for a bi-directional pickup pattern
  • Figure 18 is a top cutaway view showing a multi-partitioned configuration
  • Figure 19 and figure 20 shows two examples of the disclosed invention with extended input channels shaped in conventional horn patterns
  • Figure 21 shows the "in the enclosure” gain over the "out of the enclosure gain plotted against frequency
  • Figure 22 is a T E F spectral analysis of disclosed invention pickup sensitivity at 150 yards
  • Figure 23 is a T E F spectral analysis of a shotgun microphone's pickup sensitivity at 150 yards 6 DETAILED DESCRIPTION OF THE INVENTION
  • a waveguide (acoustic coupling device) with four key components listed below, each variable as later described, is combined to form a microphone enclosure acting as a mechanical acoustic transformer and/or filter.
  • Input channel consisting of aperture (mouth) and an acoustic coupling channel (12) with 2 or more sides (13) of varied shape and at least one sloped side shaped for efficient pressure transformer function.
  • the input channel connects the aperture (mouth) to the next component, the compression zone.
  • This component forms the output of the acoustic transformer, the end of the acoustic coupled input channel and the opening to the next component, the exit channel.
  • An exit channel (17) consists of an acoustic-coupling channel, beginning with the pressure channel or compression zone and ending in an exit port which can employ an optional termination baffle (18), (19). These four components are combined to form the instant invention.
  • an acoustic transformer is defined as an acoustic channel which mechanically connects a large area (of any desirable shape) to a small area (pressure channel, compression zone or compression chamber) of a desirable shape. Therefore at least one side of the channel forming this acoustic transformer must have a slope or varied slope in order to decrease the area of the channel progressively from input to output. From this definition it should be clear that the instant invention differentiates from the acoustic channels mentioned here from the acoustic pathways mentioned in US Patent No. 4,434,507 (Free standing transmitting microphone THOMAS).
  • the acoustic coupling channels in both the input (acoustic transformer as described above) and exit channels are shaped for the most efficient transfer of acoustic energy into and out of the compression zone, without significant reflections, within the audio spectrum desired for that application. Therefore, depending on the application the expansion (slope) of the waveguide can be linear, exponential or a combination of both. The rate of expansion and angle of the slope whether linear and/or exponential can also change. The length of these channels will also be 7 determined by application.
  • a first novel aspect of the invention is the use of a large acoustic transformer as a microphone enclosure.
  • a second novel aspect of the invention involves overcoming the usual problem of standing waves or reflected pressure, thus making it possible to use a large acoustic transformer as a microphone enclosure..
  • the problem is overcome by employing a microphone transducer in a pressure zone (barrier microphone) configuration, which will respond to the pressure gradient in the compression area while allowing the pressure to pass through unreflected (see figure 9).
  • the exit channel then facilitates the exit of the pressure, thus the occurrence of significant reflections within the waveguide are prevented, eliminating significant pressure distortion.
  • a termination baffle can be employed to absorb the sound pressure at the exit port, not allowing reflections back into the compression area as always desired, and at the same time preventing sound from another direction from entering and pressurizing the exit channel.
  • a two sided waveguide or 360-degree radial horn is used as a sound pickup device. This is achieved by suspending two dishes (see fig. 2)(convex side to convex side) with acoustically transparent standoffs (11) giving a 360-degree radial directionality.
  • the 2- sided waveguide can be made uni-directionally variable in its pickup pattern by cutting out sections of the substantially parallel dishes and inserting sound absorbing (18) material (see figure 3). This material then forms two physical sides but not acoustic channel sides.
  • a dotted line (52) indicates a waveguide side as described above.
  • the acoustic absorbing material forms the termination baffle and the pattern of this insert (18) in the enclosure determines the pickup pattern for the enclosure (see fig. 3, fig. 5 and fig. 6).
  • a single enclosure can contain several of the fundamental components (input channels (12), compression zones (15), microphone elements (14), exit channels (17), and termination baffles (18), (19) They can be placed in varied combinations forming a multiplicity of wave-guides in a single enclosure This is employed in enclosures designed for stereo (fig 11 and fig 12), bi-directional (fig 17), or quadraphonic pickup (fig 13 and fig 14)
  • This multi-channel configuration is also useful when employing a combination of waveguide components as a filter allowing for a filter-pressure amplifier combinations in the same enclosure This allows for useful forms of sound pressure equalization and/or phase cancellation notch filtering at the microphone diaphragm
  • Each waveguide within an enclosure can have its own compression zone with its own microphone, its own exit channel and its own optional termination baffle (fig 11 , fig 12, fig 13, fig 15 and fig 16)
  • its own compression zone with its own microphone, its own exit channel and its own optional termination baffle (fig 11 , fig 12, fig 13, fig 15 and fig 16)
  • several input channels can lead to a single compression zone, with one common microphone (fig 17 and fig 18) Therefore when referring to an enclosure it is understood that a single enclosure can contain a plurality of waveguides, each with its own unique purpose within the single enclosure
  • An input channel consists of an input aperture and acoustic coupling channel
  • the aperture and channel can be round, elliptical, rectangular, multi-sided (i e hexagon), or hemispherical (having a round and a flat side)
  • the aperture and waveguide can have only a top and bottom
  • the length of the input channel preferably is in the range from 0 5 inch to 36 inches Greater input channel lengths can be used, but are less practical, and are less practical
  • the channel can vary in shape, in angle of slope and rate of change of angle of slope as it progresses from mouth to compression zone
  • the channel can be a straight-line shortest distance to the compression zone, or can 9 be bent to follow a path other than the shortest distance for practical considerations (see fig 19)
  • any desired narrow to wide- angle sound pickup pattern can be achieved This can be done by adjusting the size and shape of the input channel aperture (12), acoustic channel sides (top and bottom) (13), and channeling sides (61) and/or termination baffle (18), (60), (110), (134), and (190) and reflectors (19), (111), (135), and (161)
  • the compression zone is that part of the waveguide forming the connection between the input and exit channels (15) Within the pressure channel a single or several microphone transducers (14) will always be mounted where the pressure gradient of the compression zone will be coupled to the microphone transducer d ⁇ aphragm(s) (see fig 5 for detail on microphone mounting and adjustment)
  • This microphone is mounted in the style of commercially available pressure zone or barrier microphones and will retain all the advantages for this microphone configuration
  • the barrier microphone (US Patent No 4,361 ,736) requires the diaphragm to be substantially parallel to and in close proximity to a barrier
  • the angle of the curvature of the opposing member in the proximity of the substantially parallel diaphragm will always be shallow approximating a flat barrier
  • the spacing of this diaphragm to opposing (side) member (92) will be a distance of no less than 0 025 (25 thousandths) inches
  • the microphone element (14) can be adjusted into the compression chamber (15) but there must be no flat sides perpendicular to the pressure flow shown by the arrows (10) in figure 10 To be used this way then the microphone element must be cylindrical with the round side perpendicular to the pressure flow (arrows)
  • the technique of inserting the microphone holder into the compression chamber in an adjustable fashion allows for two gaps
  • the gap shown (91) can be set for efficient acoustic transformer action and the gap shown as (101) can be set for the optimal pressure zone microphone action This advantage can be employed as long as the microphone element (figure 10-(14) does not restrict or reflect the flow of pressure through the compression chamber to the exit channel and termination baffle (as shown by arrows (10)
  • the compression zone will always, in addition to a pressure coupling to a substantially parallel microphone transducer d ⁇ aphragm(s) just described have a means for sound to enter and exit, passing through without creating significant 10 pressure reflections or pressure propagation distortion
  • the compression zone can be the same dimensions, shape or number of sides as the input and/or exit channels or can be of a different shape and number of sides respectively for the following practical consideration
  • the shape, volume, gap or gaps to microphone diaphragm, and number of sides of the pressure channel can vary independently as indicated in order to achieve the most efficient acoustic transformer match to a variety of commercially available microphone element(s)
  • These variables provide any wavegu ⁇ de(s) and m ⁇ crophone(s) comb ⁇ nat ⁇ on(s) with the desired frequency response, directivity, acoustic transformer pressure gain, efficiency and overall enclosure size for varied applications this microphone enclosure is and will be used for
  • the exit channel begins at the pressure channel and ends at exit port (17), which can have an optional termination baffle (18) and (19)
  • the purpose of this acoustic coupled channel is to provide a means for sound pressure to exit after passing through the pressure channel (compression zone or chamber)
  • the exit channel will serve as an input channel for sounds originating from its direction
  • the input channel will serve as the exit channel. It is this simultaneous vice-versa action as input channel(s) and output channel(s), depending on the direction and amplitude of sound entering the enclosure, that allows this enclosure to act as either a filter, a bi-directional pickup (fig 17), or a 360 degree radial pickup device
  • the exit channel can employ a termination baffle (18) and (19) consisting of a sound absorbing material or a combination of sound reflective (19) and absorbing material (18) This baffle will terminate the channel by allowing the sound pressure to pass through the exit channel port and be absorbed by or reflected into an absorbing chamber, thus not returning to the pressure channel or compression zone If a termination baffle is employed the exit channel and port will act as only as an exit since the termination baffle will additionally prevent any sound from entering the exit portion of the waveguide This creates a uni-directional pickup enclosure or single unidirectional waveguide within an enclosure This uni-direction pickup pattern can be set by varying the aperture of the corresponding input channel, to virtually any degree of narrow or wide angle desired (compare top cutaway views fig 5 and fig 6)
  • the exit channel and exit port can be round, elliptical, rectangular, multi-sided 11
  • the exit channel can have only a top and bottom (2 sides) as in the case of two dishes suspended back to back and parallel
  • the length of the exit channel is generally equal to or shorter than the input channel
  • the channel can vary in shape, in angle of slope and rate of change of angle of slope as it progresses from the compression zone to the exit port
  • the channel can be a straight-line shortest distance from the compression zone to the exit port, or can be bent to follow a path other than the shortest distance for practical considerations
  • the waveguides formed from these three (or four with optional termination baffle) components as described above provide useful sound pressure amplification through the acoustic transformer principle, and in some configurations these waveguides have exhibited useful filtering characteristics These characteristics in addition to making any selected microphone more sensitive, have been and are useful for pre-emphasis of sound pressure
  • This sound pressure pre-emphasis on the microphone diaphragm can be used to create a loudness curve at the output of the microphone transducer that complements the high and low frequency roll-off of human hea ⁇ ng of distance sounds, thus providing an additional perceived loudness Basically speaking it increases the sound pressure, thus providing more microphone signal strength output, in those spectral (bass and treble) regions of low human hearing sensitivity for faint or distant sounds
  • This pre-emphasis has also been employed to provide, when combined with an electronic de-emphasis equalization amplifier, noise reduction through a pre- emphasis de-emphasis scheme Additionally this pre-emphasis, particularly of treble, produces better speech intelligibility for low level voice inflection (sibilance) Vocal sound power and sibilance decrease in spectral areas where this microphone enclosure is able to increase sound pressure This has enhanced this microphone enclosure's application to conference and classroom listening and recording situations When designed to maximize treble pre-emphasis the device becomes useful in hea ⁇ ng impaired and security applications
  • this device has been incorporated with a speaker telephone (which it can be integrated into) to form a conferencing telephone It is also incorporated in intercom systems and Internet or network communications It can be wall or corner mounted It can be molded into wall panels intercom panels, computer monitors, and other fixtures for utility in communication applications and to 12 be hidden for security applications It has also been combined with a speaker as a stand alone sound transceiver
  • the microphone enclosure disclosed having one or more internal waveguides as desc ⁇ bed, is capable of reproducing ambient sound with startling cla ⁇ ty in mono, stereo or quadraphonic sound
  • the microphone enclosure disclosed is capable of reproducing ambient sound with startling cla ⁇ ty in mono, stereo or quadraphonic sound
  • it is useful in boardrooms, classrooms, therapy rooms, sales meetings, discussion groups, teleconferencing, internet or satellite conferencing, security monitoring, law enforcement, court room and legal depositions, studio recording particularly of large groups of performers (choirs or orchestras), acoustic analysis, ultrasonic, and many other like applications
  • FIGURE 2 A preferred embodiment with a 360-degree radial or panoramic pickup pattern is illustrated in FIGURE 2
  • the embodiment consists of two back to back dishes forming a radial waveguide with a top and bottom but no sides and exhibiting a radial 360-degree pickup pattern
  • the dishes are held in a substantially parallel position by acoustically transparent supports (11 ) Note that if these disks touch at their apex the waveguide is rendered non-functional
  • the sound enters between the convex portions forming the waveguide as indicated by the arrows 10 of Figure 2
  • the concave top and bottom of the dishes are covered (16) and pick up no sound
  • the circumference of the dishes can be varied as shown in the top cutaway view of Figure 8, which, while still a 360- 13 degree pickup, will vary in sensitivity around the circumference
  • sound entering from the direction of arrows (80) will be amplified more than sounds ente ⁇ ng from the direction of the smaller arrows designated (81) This allows, by varying the circumference, a microphone enclosure designed to match a particular conference table or room
  • the sound pressure filter/amplifier combination in this embodiment also delivers a large amount of spectral pre-emphasis which when combined with the proper microphone element and de-emphasis amplifier provides a means for considerable noise reduction
  • This pre-emphasis has also been used to improve speech intelligibility (sibilance) and with its 360-degree long range pickup pattern has outperformed other commercially available microphones for boardroom, classroom and conferencing applications
  • This configuration is also useful in outdoors 360-degree panoramic ambient sound recordings
  • the inherent treble pre- emphasis of this embodiment is employed to the full it is particularly useful for recording birds, bats (ultrasonic) and insects where it is of interest to record all of the above in a given location
  • the second embodiment consisting of the same elements as the first embodiment (compare fig 1 and fig 2) except for the addition of the termination baffle and a sound absorbing insert (18), (19) which makes this unit uni-directional in an application specific pattern
  • the above can be formed by one piece Top cutaway views in fig 5, fig 6, fig 11 , fig 13, and fig 20, show variable baffle insert patterns (fig 5-18), (60), (110), (134), (60)
  • the hatched areas represent the sound absorbing insert and termination baffle positions
  • acoustic foam e g SONE ⁇ X
  • Input channel can also employ four sides as shown in fig 6- (61) to enhance gain and directionality Solid lines in this view (61) designated hard waveguide sides Top and bottom are formed as shown as 13, in Figure 1
  • dotted lines (52) indicate the portion of a side formed by acoustic foam
  • the second embodiment can also use an input channel extended in what appears similar to conventional horn shape (rectangular, circular, elliptical or hemispherical), as shown in Fig 19 and Fig 20)
  • the compression channel exit channel (17) and termination baffle illustrated in these examples remain unique to the instant invention
  • the "French horn" enclosure of Fig 19, looks exotic, but is merely a coiled version of Fig 20, giving a more compact package
  • Figure 18 shows a partitioned enclosure with a common microphone (14) This is an example of a multiple-radial pickup pattern
  • the partitions (181) and sides (61) will improve the efficiency of the input channel acoustic transformer
  • This pattern is formed by partitions (170) and sides (61)
  • Figures 15 and 16 show examples of multiple waveguides in a single enclosure in a stacked configuration This is particularly useful for a stereo coincident application
  • a stereo coincident microphone the diaphragms of two microphones (14) are positioned as close as possible while still being isolated from each other and still having exclusive pickup patterns (i e right (150) and left channels (152)
  • a varied termination baffle reflector is shown (161)
  • the instant invention as illustrated in figure 15 provides this requirement with efficient acoustic transformer coupling
  • test measurements were done in an anechoic chamber using a tone sweep
  • An AUDIO PRESICION TA-1 test set was used to generate the signal, measure and record the results
  • a YAMAHA MSP5 studio monitor speaker was used to reproduce tone in the chamber
  • the microphone tested was embodiment 2, with a 6- ⁇ nch input channel, a single pressure channel gap of 0 20 of an inch, and a baffled exit channel
  • the overall diameter of the waveguide including baffle was 12 inches and the input aperture had an area of approximately 5 square inches
  • the microphone baffling was cut for a 60- degree pickup aperture
  • the microphone transducer selected was a WM-61 B supplied by PANASONIC
  • the structure of the instant invention for equal or superior performance, is more compact unit than one 2-foot parabolic and much more compact than six 2-foot parabolic microphones This makes it an excellent choice for use where parabolic microphones are now used either singly (single disclosed invention with a narrow pickup pattern) or in groups (single disclosed invention with a wide or 360-degree pattern) Its smaller size and long range variable directivity ability will extend its application beyond this existing technology (parabolic microphone) If size is not an issue for an application the instant invention in a directional embodiment can be placed in front of a parabolic dish effectively adding their respective gains to create a hyper- parabolic microphone
  • Test was done using an AUDIO CONTROL INDUSTRIAL 3050A R T A as a pink noise source The R T A also measured the sound source level at 95 db S P L
  • the speaker used (a large TRAYNOR speaker) was positioned 150 yards from both microphones The signal was recorded in stereo on a PDR 1000 HHB PORTADAT and later analyzed by a software based T E F (Time-Energy-Frequency) analyzer
  • the instant invention was configured as a 12 inch diameter single waveguide enclosure with a 6 inch input channel, a 0 2 inch gap in the pressure channel, a 1 5 inch exit channel, and a directional 180 degree termination baffle
  • the enclosure was equipped with a Panasonic WM61A electret microphone element
  • the two microphones were recorded simultaneously at a side by side location on the right and left channels of the DAT
  • the test was done in open flat 17 grassland in mid-afternoon on a calm, warm (80 degree Fahrenheit), low humidity day.
  • the microphone sensitivities were approximately matched from 500Hz to 800 Hz.
  • US Patent No. 4,831 ,656, to Southern et al discloses an angle of about 22 degrees between a flat reflector plate and a cone. According to the '656 patent the predetermined 22-degree angle of the opening between the cone and the reflector plate controls the microphone's environment by deflecting the sound waves produced by conversations into the microphone mounted within the aperture of the cone. An acoustic coupled channel is not employed in the '656 patent. Additionally, while the '656 patent does have 2 opposing sides and one sloped side as described in the instant invention, the configuration and linear angle described in the '656 patent deflection cone would be so inefficient as to have no practical value as an acoustic transformer.
  • a pressure microphone such as disclosed in US Patent No. 4,361 ,736 to Long and Wickersham, issued in 1982, the disclosure of which is incorporated herein by reference as though recited in full, is used herein for sound transduction. While the 18 structure of the instant invention bears little physical similarity to the microphone system of the '736 patent, the instant system is understood to be functioning as an enhanced pressure microphone
  • the dishes function like a pair of cups or collectors, with the sound being received within each of the two collectors
  • the space between the dishes is a null region, thereby allowing the dishes to come in contact with one another without any transmission loss
  • the sound received in the two dishes' concave side is not sensed, that is, the concave side corresponds to the null region
  • the radial 360 degree region between the convex sides of the dishes (forming a 2-s ⁇ ded waveguide-see figure 2) is the sound-receiving region, therefore requiring that the dishes be separated
  • the concave regions of the dishes are insensitive to sound and to this extent, the disclosed microphone system is not radially directional since the concave sides block sound and are usually covered, shown as16 of Figure 2 Conversely in the Botros system, the microphone
  • Botros patent and instant microphone system Another critical difference between the Botros patent and instant microphone system is that in Botros the dishes can be a portion of a small diameter sphere or ellipse, whereas in the instant invention the angle of the dished surface of the waveguide must be shallow Botros' '966 patent is not the only patent to either teach away from, or be unconcerned with the depth of the dish (angle of curvature of the waveguide)
  • US Patent No 4,831 ,656 discloses and claims an angle of about 22 degrees between a flat reflector plate and a cone
  • the predetermined 22 degree angle of the opening between the cone and the reflector plate controls the microphone's environment by deflecting the sound waves produced by conversations into the microphone mounted within the aperture of the cone
  • these sound waves enter the microphone directly or are deflected to it by the cone causing the microphone to produce a significantly higher 19 elect ⁇ cal output in the voice frequency range
  • the instant invention requires a very shallow angle at the apex or pressure channel proximate to the microphone, which can progressively open to a wide angle to maintain efficient acoustic coupling
  • the initial region and the adjacent regions require an angle substantially below 22 degrees
  • the instant system like the '656 system, and unlike '966, is responsive to sound between the two opposing members, rather than responding to sound entering one or both of such members Unlike the '656 device the members the instant invention form a waveguide with a preferred curved surface with a progressively increasing angle between the two members
  • the angle between the two members at the pressure channel, proximate the microphone must be shallow, and very substantially under the required angle of about 22 degrees of the '656 patent
  • This shaping of the spectral response can be illustrated by the comparison of a skilled musician who may be able to play a recognizable tune on a funnel but can only reproduce the full spectral beauty of the music by use of a trumpet, French horn saxophone or clarinet
  • musical instruments vary in the shape and length of their "waveguides" (all share the principle of acoustic coupling) but require very application specific waveguide shaping to produce the range of sounds they do

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Soundproofing, Sound Blocking, And Sound Damping (AREA)

Abstract

Un guide d'ondes de pression acoustique comprend un canal acoustique d'entrée, une zone de compression et un canal de sortie avec un écran terminal facultatif. La forme et la longueur des guides d'ondes varie pour ajuster le gain de pression acoustique et obtenir une directivité variée du capteur acoustique. La forme et la longueur de l'écran terminal, lorsqu'on l'utilise, sont également ajustables afin d'obtenir une directivité variée. Le guide d'ondes comprend au moins deux éléments ou faces opposés ainsi qu'au moins un élément ou une face en pente. La position de montage d'un ou de plusieurs transducteurs de microphone disponibles dans le commerce place la membrane du transducteur sensiblement parallèle au chemin acoustique dans le canal de pression du guide d'ondes. Le canal de sortie est prévu pour laisser passer la pression acoustique par le microphone jusqu'au canal de pression et à travers le guide d'ondes jusqu'à un écran terminal facultatif, empêchant ainsi une distorsion de pression significative, une distorsion par propagation de la pression acoustique et des réflexions indésirables.
PCT/CA1999/000186 1998-03-09 1999-03-09 Boitier de microphone a capteur radial WO1999046956A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
AU27069/99A AU2706999A (en) 1998-03-09 1999-03-09 Radial pickup microphone enclosure
EP99907196A EP1062837A1 (fr) 1998-03-09 1999-03-09 Boitier de microphone a capteur radial
US09/646,079 US6681023B1 (en) 1998-03-09 1999-03-09 Radial pickup microphone enclosure
CA002321670A CA2321670C (fr) 1998-03-09 1999-03-09 Boitier de microphone a capteur radial

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US7736698P 1998-03-09 1998-03-09
US60/077,366 1998-03-09

Publications (1)

Publication Number Publication Date
WO1999046956A1 true WO1999046956A1 (fr) 1999-09-16

Family

ID=22137643

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA1999/000186 WO1999046956A1 (fr) 1998-03-09 1999-03-09 Boitier de microphone a capteur radial

Country Status (4)

Country Link
EP (1) EP1062837A1 (fr)
AU (1) AU2706999A (fr)
CA (1) CA2321670C (fr)
WO (1) WO1999046956A1 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003061335A1 (fr) * 2002-01-02 2003-07-24 Advanced Bionics Corporation Ensemble microphone large bande faible bruit implantable
WO2006092841A1 (fr) 2005-02-28 2006-09-08 Fujitsu Limited Récepteur de son
EP1838131A1 (fr) * 2005-01-13 2007-09-26 Fujitsu Ltd. Recepteur de sons
US7840013B2 (en) 2003-07-01 2010-11-23 Mitel Networks Corporation Microphone array with physical beamforming using omnidirectional microphones
CN102177731B (zh) * 2008-10-22 2014-03-12 雅马哈株式会社 音频设备
CN107637095A (zh) * 2015-05-11 2018-01-26 微软技术许可有限责任公司 用于个人声音的保留隐私、能量高效的扬声器
CN109780596A (zh) * 2017-11-10 2019-05-21 宁波方太厨具有限公司 一种降噪导流装置及应用有该降噪导流装置的吸油烟机
WO2021202181A1 (fr) * 2020-03-30 2021-10-07 Plantronics, Inc. Ensemble microphone de table

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FR722263A (fr) * 1931-09-01 1932-03-15 Gilbert Procédé et dispositif pour la transmission par microphone des sons émis par un instrument
FR775846A (fr) * 1933-09-23 1935-01-10 P I A N Sa Perfectionnement aux appareils acoustiques
US4434507A (en) * 1982-08-31 1984-02-28 Chevron Research Company Free standing transmitting microphone
US4436966A (en) * 1982-03-15 1984-03-13 Darome, Inc. Conference microphone unit
WO1994022277A1 (fr) * 1993-03-19 1994-09-29 Prescom Appareil de prise et de restitution de son, et son application a l'audio-conference

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR722263A (fr) * 1931-09-01 1932-03-15 Gilbert Procédé et dispositif pour la transmission par microphone des sons émis par un instrument
FR775846A (fr) * 1933-09-23 1935-01-10 P I A N Sa Perfectionnement aux appareils acoustiques
US4436966A (en) * 1982-03-15 1984-03-13 Darome, Inc. Conference microphone unit
US4434507A (en) * 1982-08-31 1984-02-28 Chevron Research Company Free standing transmitting microphone
WO1994022277A1 (fr) * 1993-03-19 1994-09-29 Prescom Appareil de prise et de restitution de son, et son application a l'audio-conference

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2002364009B2 (en) * 2002-01-02 2007-01-25 Advanced Bionics Corporation Wideband low-noise implantable microphone assembly
WO2003061335A1 (fr) * 2002-01-02 2003-07-24 Advanced Bionics Corporation Ensemble microphone large bande faible bruit implantable
US7840013B2 (en) 2003-07-01 2010-11-23 Mitel Networks Corporation Microphone array with physical beamforming using omnidirectional microphones
US8315418B2 (en) 2005-01-13 2012-11-20 Fujitsu Limited Sound receiver
EP1838131A1 (fr) * 2005-01-13 2007-09-26 Fujitsu Ltd. Recepteur de sons
EP1838131A4 (fr) * 2005-01-13 2011-05-11 Fujitsu Ltd Recepteur de sons
CN101133677B (zh) * 2005-02-28 2012-04-04 富士通株式会社 声音接收装置
EP1855505A4 (fr) * 2005-02-28 2009-02-25 Fujitsu Ltd Récepteur de son
EP1855505A1 (fr) * 2005-02-28 2007-11-14 Fujitsu Limited Récepteur de son
US8223977B2 (en) 2005-02-28 2012-07-17 Fujitsu Limited Sound receiver
WO2006092841A1 (fr) 2005-02-28 2006-09-08 Fujitsu Limited Récepteur de son
CN102177731B (zh) * 2008-10-22 2014-03-12 雅马哈株式会社 音频设备
US8761413B2 (en) 2008-10-22 2014-06-24 Yamaha Corporation Audio apparatus with circularly arranged microphones
CN107637095A (zh) * 2015-05-11 2018-01-26 微软技术许可有限责任公司 用于个人声音的保留隐私、能量高效的扬声器
CN107637095B (zh) * 2015-05-11 2020-10-02 微软技术许可有限责任公司 用于个人声音的保留隐私、能量高效的扬声器
CN109780596A (zh) * 2017-11-10 2019-05-21 宁波方太厨具有限公司 一种降噪导流装置及应用有该降噪导流装置的吸油烟机
CN109780596B (zh) * 2017-11-10 2024-01-16 宁波方太厨具有限公司 一种降噪导流装置及应用有该降噪导流装置的吸油烟机
WO2021202181A1 (fr) * 2020-03-30 2021-10-07 Plantronics, Inc. Ensemble microphone de table
US11375319B2 (en) 2020-03-30 2022-06-28 Plantronics, Inc. Tabletop microphone assembly

Also Published As

Publication number Publication date
EP1062837A1 (fr) 2000-12-27
CA2321670C (fr) 2005-07-12
CA2321670A1 (fr) 1999-09-16
AU2706999A (en) 1999-09-27

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